Living Shoreline

Hepburn Family Preserve Living Shorelines Case Study Briefing

gzadan — Tue, 31 Aug 2021 15:46:27 +0000

Hepburn Family Preserve Living Shorelines Case Study Briefing gzadan Tue, 08/31/2021 - 11:46

Challenge

Beach and dune erosion have been an ongoing issue along the approximately 450 linear foot barrier spit that makes up the Hepburn Dune section of the Old Saybrook shoreline. The Borough of Fenwick and Lynde Point Land Trust had expended significant effort and cost to stabilize the shoreline and Lynde Point Marsh during the last 10 to 15 years. Crab Creek, located landward of the dune, was blocked by sediment and the Connecticut Department of Energy and Environmental Protection (DEEP) had made emergency repairs. Shoreline erosion continued and in 2017 there was concern that future storm events may cause a breach of the barrier spit. A breach would have negative consequences for both improved property in the area and the recently restored Lynde Point Marsh and Crab Creek located upland of the barrier spit. GZA was retained in August 2017 by the Borough of Fenwick and Lynde Point Land Trust to design a solution.

Solution

GZA proposed designing a Living Shoreline approach to mitigate ongoing erosion and reduce the potential for a breach of the barrier spit. Additional funding was necessary to complete the design process and CIRCA awarded Fenwick a Municipal Resilience Grant. Several alternatives were developed and evaluated relative to system performance, likelihood of permit acceptance and cost. GZA evaluated the performance of the Living Shoreline under prevailing wind, tide, and wave conditions (to establish requirements for new wetlands survivability) and under storm conditions (storm surge and waves) representing different recurrence intervals. The recommended alternative utilizes: 1) a nearshore wetland sill to attenuate prevailing wave heights; 2) new fill and tidal wetlands between the sill and the beach; 3) reshaping of cobble beach; and 4) dune restoration with a quarrystone-reinforced, planted dune (above the Coastal Jurisdiction Line).

Benefit

A Living Shoreline provides the benefit of a nature-based approach to shoreline stabilization, consistent with the existing barrier spit and marsh setting and with only temporary habitat impact. This approach also addresses the erosive effects of existing, historical coastal structures located near the site. GZA assisted the Borough with an application for a CIRCA Municipal Resilience Grant which was awarded. The project was designated by DEEP as a pilot demonstration project with long term performance monitoring. GZA collaborated with CIRCA and the University of Connecticut to establish empirical Living Shoreline performance criteria applicable to Long Island Sound. The project was also recently presented by CIRCA as part of a Living Shoreline permit workshop.

Project Design

GZA is at the forefront of Living Shoreline and hybrid system design for coastal shoreline stabilization. GZA’s approach has been to integrate ecology and coastal engineering technologies to develop a rational method for design of Living Shorelines, and utilizes:

Detailed statistical analysis of wind, water level and wave data;
Assessment of the environmental stress conditions required for new marsh survivability (based on tidal elevation and prevailing wave height and frequency);
Use of high-resolution numerical wave and surge modeling;
Risk-based design which evaluates the system response under a range of conditions (from prevailing conditions to different recurrence interval coastal flood conditions), and;
Consideration of the state and local regulatory agency goals for living shorelines during design.

GZA used a very high resolution, 2-dimensional numerical wave model (SWAN) to characterize nearshore waves. The results of the wave modeling were used to: 1) determine the need for wave attenuation (for new marsh survivability); and 2) inform placement of the Living Shoreline features (e.g., wetlands and rock sills) to conform to the existing shoreline geomorphology and tidal and wave currents. This design approach enhances shoreline stabilization while avoiding significant habitat impact and creating additional erosion in the vicinity.

GZA’s SWAN modeling results of the prevailing wave conditions confirmed that the prevailing wave heights exceed marsh survivability criteria and new wetland sills will be required for wave attenuation. The project is on the southern facing shoreline, with a long fetch across Long Island Sound. GZA’s risk analysis established a probability-based design basis, which defines the performance of the system in terms of likelihood of failure and predicted frequency of maintenance.

GZA completed the permitting in one year. Construction began in 2020 and was completed on May 15, 2021.

CIRCA Municipal Resilience Grant application and award
Living Shoreline proposed for stabilization of barrier spit
State DEEP pilot demonstration project
Historical shoreline change assessment
Metocean data analysis
Numerical wave modeling
Numerical cross-shore sediment transport modeling
Living shoreline design, permitting and construction monitoring
Project Partners: Lynde Point Land Trust, Borough of Fenwick, CIRCA, Connecticut River Conservancy, Sea Grant Connecticut, State of Connecticut DEEP, SumCo Eco-Contracting (construction) and several individual and philanthropic funding partners
Connecticut Green Building Council 2022 Green Building Awards- Resilience Award of Honor

Waterfront and Coastal Engineering

Rose Larisa Park Living Shoreline Protection

gzadan — Mon, 24 Aug 2020 16:02:19 +0000

Rose Larisa Park Living Shoreline Protection gzadan Mon, 08/24/2020 - 12:02

The Rhode Island Coastal Resources Management Council (CRMC) and The Nature Conservancy (TNC) received funding from the National Oceanic and Atmospheric Administration (NOAA) Coastal Resiliency Grant Program to increase coastal resilience and reduce risk to people, infrastructure and natural resources in coastal communities by building and monitoring nature-based coastal infrastructure throughout New England. TNC raised additional matching funds with grants from 11th Hour Racing and the RI Coastal and Estuarine Habitat Restoration Trust Fund, administered by CRMC. The objective of the program is to identify and test living solutions to improve shoreline protection and monitor the results over time. The Rhode Island project included the construction and monitoring of two bluff erosion control treatments for the purpose of stabilizing the bluff and creating salt marsh for beach protection at Rose Larisa Park in East Providence, RI.

Challenge

GZA GeoEnvironmental, Inc. (GZA) teamed with SumCo Eco-Contracting of Peabody, MA to provide engineering design, permitting support, and construction services for the design and construction of two bluff erosion control treatments including a biodegradable shoreline with appropriate plantings and an intertidal sill along the beach below the bluff at the park on the Providence River.

Solution

GZA completed a site visit and reviewed the provided topographic survey of the beach and bluff area to establish the base plan for the design of the treatments. Design plans were developed and reviewed with TNC and CRMC. GZA also provided sketches for inclusion in permitting documents prepared by TNC and CRMC. Following reviews and approvals, the construction of the proposed designs was completed. Construction was performed by SumCo Eco-Contracting under the watchful eye of The Nature Conservancy. Volunteers from CRMC, TNC and Save the Bay helped with planting efforts during construction.

Benefit

The installation of the living shoreline protections will be monitored for their efficacy and resilience over time. The success of these treatments will help determine if these methods will be utilized more frequently for shoreline protection in Rhode Island and throughout New England.

Completed site visits and reviewed available topographic survey to establish base condition
Prepared design documents for review and approvals
Assisted in preparation of permit documents
Provided Construction Phase Services

Water

Waterfront and Coastal Engineering

Natural Resources and Ecological Services

Natural Hazard Risk Management, Climate Adaptation and Resilience

Long Wharf Flood Protection Study and Living Shoreline Design

Anonymous — Mon, 23 Sep 2019 14:07:14 +0000

Long Wharf Flood Protection Study and Living Shoreline Design Anonymous Mon, 09/23/2019 - 10:07

Challenge

The Long Wharf area of New Haven, located within FEMA VE and AE high risk flood hazard zones, is highly vulnerable to coastal flooding. It has historically experienced severe flooding and flood damage from hurricanes and extreme weather events dating to the Hurricane of 1938 and more recently during Hurricane Irene and Superstorm Sandy. Improved resilience to coastal flooding is imperative to the social, economic and ecological resilience of the City of New Haven and the region.

Solution

GZA implemented a flood protection study in the Long Wharf District of New Haven. The District consists of two distinct areas in their character and use: the waterfront shoreline and the industrial district. The Long Wharf Flood Protection Study included planning and design of coastal flooding mitigation and shoreline protection measures for the area located northwest of the Long Wharf shoreline to Union Avenue. An inter-disciplinary team led by GZA completed a detailed flood vulnerability analysis in the project area. Based on the results of the vulnerability analysis, the team identified flood control strategies that not only addressed economic concerns related to business disruption after flooding but also identified ways in which the flood mitigation alternatives benefit the general public by creating a visionary plan for the City to improve social, economic, and ecological resilience to sea level rise, local intense precipitation, storm surge, and erosion. GZA’s project team includes Utile, Biohabitats, and Cambridge Systematics.

GZA’s project approach was multidisciplinary, and the team:

Incorporated industry-accepted science for sea level rise and coastal flooding;
Performed statistical analysis on historical storm surge flood level data from relevant water level stations, such as those from National Oceanic and Atmospheric Administration (NOAA);
Used high resolution terrain data (post-Sandy);
Completed high resolution, hydrodynamic computer flood modeling to characterize coastal flooding and its effect on structures and natural features;
Created scenario-based flood maps to evaluate the vulnerability of the area to tides and storm surges;
Managed all information using Esri ArcGIS geographic information system (GIS) software;
Used a “risk-based�� approach, defining coastal flood hazards in terms of probability, consistent with methods currently being used by state and federal agencies; and
Identified resiliency strategies and alternatives that are consistent with City of New Haven’s current vision and plans for development.

The design includes an integrated approach to flood protection, shore protection, and environmental and ecological benefits, including a seawall, a buried revetment, timber walkway, beach nourishment and wetland enhancement, tidal flats, and oyster reef submerged breakwaters. This plan also creates a new level of access and usability of the shoreline by the public.

Benefit

The study identified strategies relevant to the character of the neighborhoods and areas to reduce coastal flooding in the district. It is also used as a road map for the City for creating social, economic, and ecological resilience in relation to future sea level rise impacts, storm surge, and erosion.

GZA’s permit-level design for the proposed Long Wharf Flood and Shoreline Protection project enables the City of New Haven to move forward quickly with final design and construction as funding is secured. The comprehensive analysis and design acknowledges that a resilient New Haven is critical to Connecticut and creates the resiliency features necessary to foster social, economic, and ecological health of the area.

Insights

US HUD CDBG-Disaster Recovery Grant
FEMA Building Resilient Infrastructure and Communities (BRIC) Grant
Review of Existing Plans
Vulnerability and Risk Assessment
Adaptation Options Analysis
Stakeholder Identification and Engagement
Public Information Meetings
Living Shoreline Design
Feasibility Analysis of Flood Mitigation Strategies

Connecticut

Water

Government

Waterfront and Coastal Engineering

Natural Hazard Risk Management, Climate Adaptation and Resilience

Land Use and Environmental Planning

Natural Resources and Ecological Services

Data Management, Analytics and Visualization Solutions

Encore Boston Harbor Resort and Casino

Anonymous — ��Ϸ��d, 18 Sep 2019 18:52:40 +0000

Encore Boston Harbor Resort and Casino Anonymous ��Ϸ��d, 09/18/2019 - 14:52

Challenge

The 32-acre property on the Mystic River selected for the Encore Boston Harbor resort and casino had been impacted by historic chemical manufacturing use; much of the site was on salt marsh that had been filled with waste materials from operations at the site and/or nearby facilities. The buildings on the property were razed in the 1970s and the property had been used primarily as a material storage and staging yard since the mid-1990s, when rock and fine-grained material (“tunnel muck��) from the construction of the Deer Island Outfall project were stockpiled on it and later spread out. In addition, the geologic conditions varied greatly within the site. The combination of complex environmental and geologic conditions, coastal flood vulnerability, the waterfront setting, and the fast-paced nature of this mega-development project required a focused project team with a diverse set of technical skills.

Solution

During initial phases of the project, GZA participated in negotiations with the former owner regarding the extent of remediation warranted by site conditions. GZA also prepared several sections of the reports required by the Massachusetts Environmental Policy Act (MEPA), and developed cost estimates for reaching regulatory closure under the Massachusetts Contingency Plan (MCP) and for dealing with contamination encountered during construction. To meet the growing needs of the project, GZA’s involvement quickly grew to include geotechnical and marine engineering as well as comprehensive natural resources and permitting services.

Ecological Services and Resilient Design: GZA’s natural resources team conducted topographic and hydrographic surveys; performed biological surveys of the shoreline, intertidal, and sub-tidal zones; conducted extensive sediment sampling and analysis to further define the nature and extent of sediment impacts from historic operations; characterized sediments within a former ship channel to identify costs associated with dredging and reopening the channel for the project’s use; and developed plans for a Living Shoreline to return the native salt marsh and native coastal bank plant species to the fringe of the site as part of the environmental impact mitigation for the project.

Geotechnical Engineering: GZA developed geotechnical foundation design recommendations to support the 29-story tower as well as the low-rise portions of the project. With a large portion of the building footprint constructed over a multilevel garage, groundwater control was an important issue for both construction and building design. GZA evaluated foundation, groundwater control, and lateral earth support options, taking into account both the extent and depth of the basement, and both geotechnical and environmental considerations. Given the variety of building loads and subsurface conditions, multiple foundation types were utilized: slurry walls for excavation support and the support of building loads; load-bearing elements to support the tower; precast prestressed concrete piles and drilled mini piles to support low rise portions of the building; a mat foundation for the majority of the below-grade garage; and rock tiedowns to help resist hydrostatic uplift pressures.

Environmental Services: GZA designed and implemented remedial activities to address three highly contaminated areas of the site prior to building construction. In one area, in-situ stabilization was used to help neutralize low-pH groundwater. In two other areas with elevated concentrations of metals, soils were excavated and replaced. While providing Licensed Site Professional (LSP) services for the project, GZA pre-characterized and drafted disposal documentation for over 800,000 tons of soil removed from the site during building and site construction.

Waterfront Engineering: GZA was also responsible for the resilient design of the project’s waterfront marina, with over 600 linear feet of bulkhead and a 300-foot-long floating dock. Due to the soft soils at the site, a load-transfer platform was designed to support new loads and mitigate settlement concerns.

Benefit

At a total estimated design and construction value of $2.6 billion, the Encore Boston Harbor resort and casino is the largest single-phase private development in Massachusetts history. By nimbly responding to changes to the proposed project during construction, GZA was able to provide the multidisciplinary services and management skill required to help move this high-profile, technically-challenging project forward to an on-time completion date.

Insights

Comprehensive permitting/ ecological, marine, environmental and geotechnical services
Sediment sampling/analysis
Living Shoreline design
Remedial design and construction
Precharacterization program
LSP services
Geotechnical design for below-grade garage and 29-story tower
Design of floating dock, bulkhead, and load relief platform
Construction phase services
Sustainable and resilient design
2020 EBC James D.P. Farrell Award for Brownfields-Remediation Project of the Year

Massachusetts

Buildings & Real Estate Development

Water

Geotechnical Engineering Services

Environmental Site Investigation & Remediation

EHS Regulatory Compliance

Natural Resources and Ecological Services

Waterfront and Coastal Engineering

Construction Management

Data Management, Analytics and Visualization Solutions